Not Applicable.
Not Applicable.
1. Field of the Invention
The present invention relates to valves. More particularly, the present invention is directed to electronically-actuatable valves adapted for controlling the injection of a fuel into an engine.
2. Description of the Background
Many conventional engines of all fuel types including gasoline and diesel typically employ a fuel injector for supplying known quantities of fuel to each combustion chamber at precise times during the engine cycle. Typically, a fuel injector assembly is mounted on the engine cylinder head of a combustion chamber. The fuel injector functions to open and close the fuel pump supply line to each engine cylinder head when commanded to do so by an electrical signal from the engine control computer.
One type of conventional fuel injector is a one-piece electromechanical assembly having a housing, a spring-loaded armature of magnetically permeable material and an electromagnetic coil adjacent the armature that is axially positioned within a fuel supply passage. The housing surrounds both the armature and coil. The electrical wires must pass through this housing without leakage and must be electrically isolated from the housing. When this fuel injector is unenergized, the valve is closed and the armature is held against a valve seat by spring and hydraulic forces to prevent fuel from entering the engine cylinder head. As an electrical current is passed through the electromagnetic coil, a magnetic field is created. When the force from the magnetic field becomes sufficient to overcome the hydraulic and spring forces, the armature will be urged away from the valve seat and fuel will pass through the engine cylinder head to the combustion chamber. When the electrical energy is no longer supplied to the electromagnetic coil, the magnetic force starts to decay and the spring and hydraulic forces then become dominant and move the armature against the valve seat to the closed position.
One disadvantage of this type of conventional fuel injector is that it is difficult to accommodate all of the components of the fuel injector within the limited amount of space available in a reciprocating, opposed cylinder aircraft engine. In many aircraft engine arrangements, for example, the minimum diameter of space for a fuel injector is less than 0.75 inches. Fuel injectors used in automotive applications occupy a space with a diameter of about 1.25 inches. Thus, sufficient room is not available within the aircraft engine envelope to accommodate the available automotive-type fuel injector components and also to provide for installation and removal of the fuel injector components from the engine cylinder head port.
Existing fuel injector assembly internal designs are also complicated by the need to connect electrical signals across internal fuel to air barriers, together with requiring the means to operate the internal electromagnetic components in a fuel wetted environment. The sealing arrangements needed to address this problem, besides impacting size and weight, also preclude separate replacement of electrical and fluid handling elements within the assembly. Therefore, the entire assembly must be discarded in the event of a single failure in either element. Such one-piece construction also prevents the desirable use of a threaded port for installation to the engine cylinder head or inlet manifold, because it would not be practical to rotate the complete assembly.
Yet another disadvantage with conventional fuel injectors is that the electromagnetic coil and electrical supply cable are located within the same unit as the fuel passageway. Thus, the electromagnetic coil and the electrical supply cable are susceptible to decay caused by fuel and fuel vapor. As such, coil wire insulation material has to be carefully selected so as to not break down in the presence of fuel or fuel vapors should internal seepage occur despite such sealing arrangements. Such requirements place restrictions on the overall assembly design which result in injector assemblies that are difficult to accommodate within the engine envelope due to their physical size. It also requires that the electrical coil and connection structure be an integral, non-removable part of the injector assembly housing. Such condition also necessitates injector installation to the engine as a complete assembly, not permitting the use of a threaded installation port.
Accordingly, there is a need for a fuel injector that is compact and that can be easily installed and removed from an engine.
The need also exists for a fuel injector that has an electromagnetic coil and an electrical supply cable that can be readily separated from the mechanical valve components of the fuel injector, such that the mechanical portion of the valve can be replaced without also replacing the valve""s electrical component or the electrical components can be replaced without also replacing the mechanical portion of the valve.
Yet another need exists for a fuel injector assembly that can be readily attached to the cylinder head of an engine by a threaded port arrangement.
Still another need exists for injecting a fuel into the combustion chamber of an engine that does not require the use of prior bulky fuel injectors which lead to increased engine weight and engine size.
The present invention provides a valve having an inner housing with an outlet port, a stopper member movably supported within the inner housing, a central housing member received within the inner housing and a magnetic flux that travels in a loop though the inner housing and the stopper member such that the magnetic flux urges the stopper member from a closed position, wherein the stopper member blocks the outlet port to an opened position.
The present invention further provides a valve having an inner housing of magnetically permeable material, a stopper member of magnetically permeable material, a central housing member of non-magnetically permeable material and an electrically-energizeable coil adjacent the inner housing, wherein the central housing member acts as a shunt such that the magnetic flux created by the coil bypasses the central housing member and travels through the stopper member.
The present invention further provides a fuel injector having an inner housing of magnetically permeable material with a valve passage and an outlet port, a valve stem movably received with the valve passage between a closed position, wherein the valve stem blocks the outlet port and an opened position, a biaser in contact with the valve stem, and an electrically-energizeable coil extending around at least a portion of the central housing member and adjacent the inner housing such that upon an application of current to the electrically energizeable coil, a magnetic flux is established within the magnetically permeable materials of the inner housing and the valve stem to cause the valve stem to move to the opened position. The inner housing of the fuel injector may be releasably connected to a cylinder head of an engine such as an aircraft engine.
The present invention further provides a two-part electromechanical valve having an electrical assembly and a fluid handling assembly, wherein these two separate assemblies provide a sealing arrangement that isolates the electrical components from the fluid that is passing through the valve. The electrical assembly includes a magnetically permeable cover with an opening for receiving an electrical supply cable, a bobbin inserted inside the cover, potting material contained within the cover and an electrically-energizeable coil wound around the bobbin and able to be electrically connected to the electrical supply cable. The fluid handling assembly includes a housing having a fluid passage that receives a stopper member and the fluid handling assembly is releasably connected to the electrical assembly using a connector.
The present invention further provides a method of injecting fuel into an engine comprising attaching an inner housing of a fuel injector to an engine, wherein the inner housing is made of magnetically permeable material with an outlet port and a passage, and the fuel injector further comprises a stopper member of magnetically permeable material and a central housing member of nonmagnetically permeable material, and wherein the stopper member is received within the inner housing, and the central housing member is received within the inner housing and adjacent the stopper member; transporting fuel into the passage; supplying fuel to the passage; and creating a magnetic flux through the inner housing and the stopper member such that the magnetic flux urges the stopper member from a closed position, wherein it blocks the outlet port, to an opened position.
Other details, objects and advantages of the present invention will become more apparent with the following description of the present invention.